“It [plastic] is now of a proportion and scale that it has taken over from the traditional building material. It’s like looking at a rubbish tip,” said Vincent Hyland, a locally based conservationist and film-maker.

He says there are two sources: pollution in Irish rivers and along the coast, and the dumping of other materials, especially fishing gear, from further out and as far away as Newfoundland and Maine.

“It could take 15 to 20 years to come here but it’s coming across the Atlantic,” he said. Filming underwater since the 1970s, Mr Hyland said he had seen the pollution gradually increase but rising to “frightening proportions” in the last year.

He is concerned the problem is being ignored by authorities more concerned with marketing the islands to tourists – the neighbouring Skellig Michael has become a massive draw following its use as a location in recent Star Wars movies. It had almost 14,700 visitors in 2016.

“I film marine life underwater [and] it’s very difficult to get a frame without plastic in it, and that wasn’t an issue 15 years ago,” Mr Hyland said.

Little Skellig is the largest gannet colony in Ireland and, according to Birdwatch Ireland, it continues to grow.

Bird reservation

Fianna Fáil Senator Mark Daly is due to raise the issue in the Seanad next week and says he has been contacted by local boat operators relaying the concerns of tourists taken out to look at the island’s bird reservation.

“It’s an issue from a tourist point of view and from an environmental point of view as well. That the oceans are in such shape is unacceptable obviously; it’s a broader issue,” he said.

Dr Stephen Newton, BirdWatch Ireland’s senior seabird conservation officer who has spent a lot of time on the Skellig Islands, said the material being used to build nests is mostly polypropylene rope and other fishing material.

“I agree that a lot of that material gets into the nests [but] by and large it doesn’t do any harm,” he said, adding that of far more concern to bird health were smaller pieces of ingested plastic. However, the image of Little Skellig covered in discarded material, he said, “sends a strong message”.

Nests of rope

“If you look at 100 gannet nests and most of them have a blue or orange rope in them, it’s not great.”

The National Parks and Wildlife Service said it was concerned about the possibility of harm to birds caused by waste.

“It is apparent when approaching Little Skellig that gannets use plastic waste material when constructing their nest sites and although we do not have records of specific instances where birds have died from this, or have been tangled up in such litter, it has been shown to be an issue elsewhere in the species’ range and is a matter of concern,” it said in a statement.

However, it pointed out the bird population had increased by 60 per cent since the late 1960s. “The National Parks and Wildlife Service deplores and strongly condemns the dumping of waste anywhere in our natural habitats, and is looking into this matter.”